Compositions and methods for hemoglobin production

ABSTRACT

Methods and compositions for producing fetal hemoglobin and treating a hemoglobinopathy or thalassemia are disclosed.

This application is a continuation application of U.S. patent application Ser. No. 16/478,651, filed Jul. 17, 2019, which is a § 371 application of PCT/US2018/015918, filed Jan. 30, 2018, which claims priority under 35 U.S.C. § 119(e) to U.S. Provisional Patent Application No. 62/452,069, filed Jan. 30, 2017 and U.S. Provisional Patent Application No. 62/465,283, filed Mar. 1, 2017. The foregoing applications are incorporated by reference herein.

This invention was made with government support under Grant Nos. R37DK058044, R01DK054937, and R01HL119479 awarded by National Institutes of Health. The government has certain rights in the invention.

FIELD OF THE INVENTION

The present invention relates to the field of hematology. More specifically, the invention provides compositions and methods for the production of various forms of hemoglobin, including adult and fetal type hemoglobin.

BACKGROUND OF THE INVENTION

Several publications and patent documents are cited throughout the specification in order to describe the state of the art to which this invention pertains. Each of these citations is incorporated herein by reference as though set forth in full.

Sickle cell disease and thalassemia cause significant worldwide morbidity and mortality (Modell et al. (2008) Bull. World Health Org., 86:480-487). However, effective drugs do not exist for these illnesses. One goal in the treatment of these diseases is to reactivate fetal hemoglobin (HbF). HbF reduces the propensity of sickle cell disease red blood cells to undergo sickling. Indeed, high fetal globin levels are associated with improved outcomes for sickle cell anemia patients (Platt et al. (1994) N. Engl. J. Med., 330:1639-1644). Elevating HbF also reduces the globin chain imbalance in certain thalassemias, thereby improving symptoms. There is an enormous unmet need to identify compounds that ameliorate the course of these diseases.

SUMMARY OF THE INVENTION

In accordance with the present invention, compositions and methods are provided for increasing hemoglobin levels (e.g., fetal hemoglobin) in a cell or subject. In a particular embodiment, the method comprises administering at least one eIF2αK1 inhibitor to the cell or subject. In a particular embodiment, the subject has a hemoglobinopathy such as sickle cell disease or thalassemia. In a particular embodiment, the cell is an erythroid cell. In a particular embodiment, the eIF2αK1 inhibitor is a small molecule. The eIF2αK1 inhibitor may be, for example, a kinase domain inhibitor or a heme binding domain inhibitor. The eIF2αK1 inhibitor may be a CRISPR based or siRNA/shRNA based inhibitor of the eIF2αK1 gene. The method may further comprise delivering at least one fetal hemoglobin inducer to the cell or subject. The method may further comprise the administration of other fetal hemoglobin inducing methods (e.g., pharmacologic compounds or various forms of gene therapy) in order to produce additive or synergistic effects.

In accordance with another aspect of the instant invention, methods of inhibiting, treating, and/or preventing a hemoglobinopathy (e.g., sickle cell disease or thalassemia) in a subject are provided. In a particular embodiment, the method comprises administering at least one eIF2αK1 inhibitor to a subject in need thereof. The eIF2αK1 inhibitor may be in a composition with a pharmaceutically acceptable carrier. In a particular embodiment, the subject has a β-chain hemoglobinopathy. In a particular embodiment, the subject has sickle cell anemia. In a particular embodiment, the eIF2αK1 inhibitor is a small molecule. The eIF2αK1 inhibitor may be, for example, a kinase domain inhibitor or a heme binding domain inhibitor. The eIF2αK1 inhibitor may be a CRISPR based or siRNA/shRNA based inhibitor of the eIF2αK1 gene. The method may further comprise delivering at least one other fetal hemoglobin inducer to the subject.

BRIEF DESCRIPTIONS OF THE DRAWINGS

FIG. 1A is a graph of the percentage of cells that are positive for fetal hemoglobin (HbF) expression. Human umbilical cord blood-derived erythroid progenitor cells (HUDEP-2) expressing Cas9 were transduced with one of the six guideRNAs targeting eIF2αK1; a guideRNA targeting BCL11A exon 2 (positive control; BCL11A is a repressor of HbF expression); one of two guideRNAs targeting death associated protein kinase 2 (DAPK2); one of two guideRNAs targeting transforming growth factor beta receptor 2 (TGFBR2); or a negative control guideRNA. FIG. 1B is a graph of the gamma globin mRNA levels in the cells of FIG. 1A. A negative control of untreated cells is also provided. FIG. 1C is a representative HbF FACS analysis for HUDEP-2 cells expressing sgRNA #5 or non-targeting sgRNA. FIG. 1D is a graph of the percentage of HUDEP-2 cells that are positive for HbF expression. Mean is shown±standard deviation from biological replicates (n=2). FIG. 1E is a Western blot analysis of various proteins in HUDEP-2 cells transduced with BCL11A exon 2 sgRNA, sgRNA #3, sgRNA #5, or non-targeting sgRNA.

FIG. 2 provides the results of a whole proteome mass spectrometry analysis of cells transduced with a guideRNA targeting eIF2αK1 compared to a negative control guideRNA. Left panel is for cells transduced with eIF2αK1 sgRNA #3 and right panel is for cells transduced with eIF2αK1 sgRNA #5. Black ovals with arrow indicate fetal globin expression. White ovals—zeta globin; ovals with vertical lines—adult β-globin; ovals with horizontal lines—adult α-globin. Vertical dashed lines indicate a 2 fold change. Horizontal dashed line indicates a p-value of 0.01.

FIG. 3 is a graph of the percentage of cells positive for HbF expression. HUDEP-2 expressing Cas9 cells were transduced with eIF2αK1 sgRNA #3, eIF2αK1 sgRNA #5, a gRNA targeting BCL11A exon 2, or a negative control gRNA. Cells were then incubated with or without pomalidomide. n=3.

FIG. 4 provides graphs of the expression of HbF in human primary cells treated with eIF2αK1 shRNA, BCL11A shRNA, or scrambled shRNA (negative control).

FIG. 5A provides representative HbF flow cytometry on day 14 of CD34+ erythroid differentiation. FIG. 5B provides a graph of HbF flow cytometry experiments. Error bars: SEM from 3 independent donors (* denotes p-value <0.05, ** denotes p-value <0.01 from unpaired student T-tests). FIG. 5C shows γ-globin mRNA as fraction of γ-globin+β-globin by RT-qPCR on day 12. Error bars: SEM from 3 independent donors (* denotes p-value <0.05, ** denotes p-value <0.01 from unpaired student T-tests). FIG. 5D shows the RNA-seq for CD34+ cells on day 12. R-value denotes Pearson correlation coefficient. Data was obtained from one patient donor. FIG. 5E shows HPLC analysis of samples from cell expressing annotated shRNAs, at day 14 of differentiation. HbA: hemoglobin A (adult form). HbF: fetal hemoglobin. Error bars: standard deviation from 2 independent donors. FIG. 5F provides images of sickle cell patient-derived erythroid cultures. Arrow heads mark cells with sickle-like morphology. Bar graph: summary of blindly counted sickle shaped cells from 3 fields from one patient with sickle cell disease.

FIG. 6A provides a Western blot with indicated antibodies in cells uninfected, or infected with virus expressing scrambled or HRI shRNAs on day 14 of differentiation (left). BCL11A mRNA levels in HRI knock down cells as fraction of SC shRNA expressing cells is also shown (right). Error bars standard deviation from two biological replicates. FIG. 6B shows RT-qPCR for γ-globin as a fraction of γ-globin+β-globin in a BCL11A cDNA rescue in HRI depleted HUDEP2 clonal cell line. Error bars: standard deviation from two biological replicates.

FIG. 7A provides an example of an amino acid sequence (SEQ ID NO: 19) of eIF2αK1 and FIGS. 7B and 7C provide an example of a nucleotide sequence (SEQ ID NO: 20) encoding eIF2αK1.

DETAILED DESCRIPTION OF THE INVENTION

A major goal in the treatment of sickle cell disease and thalassemia is the reactivation of fetal type globin expression in cells of the adult red blood lineage. In an unbiased genetic screen, the protein kinase eIF2αK1 (eukaryotic translation initiation factor 2-alpha kinase 1; also known as Heme-Regulated Inhibitor (HRI)) was identified as a strong regulator of fetal globin production. eIF2αK1 (see, e.g., PubMed GeneID: 27102; see, e.g., GenBank Accession Nos. NP_055228, NP_001127807, NM_001134335, and NM_014413) is a protein kinase that phosphorylates the translation initiation factor eIF2a and regulates protein translation (Klann et al. (2004) Nat. Rev. Neurosci., 5:931-942).

The activation of the pathway controlled by eIF2αK1 has been associated with a modest increase in HbF (Hahn et al., Blood (2013) 122(4):477-85; Han et al., EMBO J. (2001) 20:6909-6919). However, in complete contrast, it is shown herein that the inhibition of eIF2αK1 raises fetal hemoglobin levels. Indeed, the genetic screen described herein for HbF inducers in human cells indicates that the loss of eIF2αK1 function increases HbF levels. Indeed, additional experiments show that the loss of eIF2αK1 increases fetal hemoglobin production in human erythroid cells, including primary cells. Without being bound by theory, the mechanism by which this occurs likely involves transcriptional and translational upregulation of fetal hemoglobin production. Thus, the role of eIF2αK1 in the suppression of fetal and, to a lesser extent, embryonic globin production has been shown herein. This role is exploited herein to treat hemoglobinopathies such as sickle cell anemia and thalassemia.

As a protein kinase, eIF2αK1 has a kinase domain that can be inhibited (e.g., by a small molecule). Additionally, eIF2αK1 can be inhibited by its natural ligand heme. This inhibition can be exploited for designing new inhibitors of eIF2αK1 (e.g., small molecule ligands that mimic heme). The kinase domain inhibitors and heme binding domain inhibitors can be used individually or in combination. Inasmuch as eIF2αK1 is expressed almost exclusively in erythroid cells, its inhibition will have little or no impact on other tissues or cells. Indeed, mice in which eIF2αK1 is deleted are fertile, appear normal, and do not present any gross abnormalities (Han et al., EMBO J. (2001) 20:6909-6919).

In accordance with the instant invention, compositions and methods are provided for increasing hemoglobin production in a cell or subject. In a particular embodiment, the method increases fetal hemoglobin and/or embryonic globin expression, particularly fetal hemoglobin. The method comprises administering at least one eIF2αK1 inhibitor to the cell, particularly an erythroid precursor cell or erythroid cell, or subject. In a particular embodiment, the subject has a hemoglobinopathy such as sickle cell disease or thalassemia. In a particular embodiment, the subject has sickle cell anemia. The eIF2αK1 inhibitor may be administered in a composition further comprising at least one pharmaceutically acceptable carrier. The methods of the instant invention may comprise administering at least two different eIF2αK1 inhibitors (e.g., two different mechanisms of action), particularly one kinase domain inhibitor and at least one heme binding domain inhibitor. In a particular embodiment, the method further comprises any means by which to induce fetal hemoglobin, such as administering at least one other fetal hemoglobin inducer. Fetal hemoglobin inducers include, without limitation, a lysine-specific demethylase 1 (LSD1) inhibitor (e.g., RN-1 (Cui et al. (2015) Blood 126(3):386-96) and tranylcypromine (TCP) (Sun et al. (2016) Reprod. Biol. Endocrinol., 14:17)), pomalidomide, hydroxyurea, and 5-azacytidine, sodium butyrate, activators of the Foxo3 pathway (e.g., metformin, phenformin, or resveratrol), histone methyltransferase (HMT) inhibitors (e.g., a histone lysine methyltrasnferase inhibitor, euchromatic histone-lysine N-methyltransferase 2 (EHMT2; G9a) inhibitor, euchromatic histone-lysine N-methyltransferase 1 (EHMT1; G9a-like protein (GLP)) inhibitor, UNC0638 (2-cyclohexyl-N-(1-isopropylpiperidin-4-yl)-6-methoxy-7-β-(pyrrolidin-1-yl)propoxy) quinazolin-4-amine), chaetocin, BIX-01294, UNC 0224, UNC 0642, UNC 0631, UNC 0646, A-366 (Sweis et al. (2014) ACS Med. Chem. Lett., 5(2):205-209), etc.), and histone deacetylase (HDAC) inhibitors. In a particular embodiment, the fetal hemoglobin inducer is a histone methyltransferase (HMT) inhibitor, particularly UNC0638. In a particular embodiment, the fetal hemoglobin inducer is pomalidomide or hydroxyurea, particularly pomalidomide. The eIF2αK1 inhibitor and the fetal hemoglobin inducer can be delivered to the cell or subject sequentially or consecutively (e.g., in different compositions) and/or at the same time (e.g., in the same composition).

In accordance with another aspect of the instant invention, compositions and methods for inhibiting (e.g., reducing or slowing), treating, and/or preventing a hemoglobinopathy or thalassemia in a subject are provided. In a particular embodiment, the methods comprise administering to a subject in need thereof a therapeutically effective amount of at least one eIF2αK1 inhibitor. The eIF2αK1 inhibitor may be administered in a composition further comprising at least one pharmaceutically acceptable carrier. In a particular embodiment, the hemoglobinopathy is β-thalassemia or sickle cell anemia. In a particular embodiment, the subject has sickle cell anemia. The methods of the instant invention may comprise administering at least two different eIF2αK1 inhibitors (e.g., two different mechanisms of action), particularly one kinase domain inhibitor and at least one heme binding domain inhibitor. In a particular embodiment, the method further comprises administering at least one other fetal hemoglobin inducer to the subject. Fetal hemoglobin inducers include, without limitation, a lysine-specific demethylase 1 (LSD1) inhibitor (e.g., RN-1 (Cui et al. (2015) Blood 126(3):386-96) and tranylcypromine (TCP) (Sun et al. (2016) Reprod. Biol. Endocrinol., 14:17)), pomalidomide, hydroxyurea, and 5-azacytidine, sodium butyrate, activators of the Foxo3 pathway (e.g., metformin, phenformin, or resveratrol), histone methyltransferase (HMT) inhibitors (e.g., a histone lysine methyltrasnferase inhibitor, euchromatic histone-lysine N-methyltransferase 2 (EHMT2; G9a) inhibitor, euchromatic histone-lysine N-methyltransferase 1 (EHMT1; G9a-like protein (GLP)) inhibitor, UNC0638 (2-cyclohexyl-N-(1-isopropylpiperidin-4-yl)-6-methoxy-7-(3-(pyrrolidin-1-yl)propoxy) quinazolin-4-amine), chaetocin, BIX-01294, UNC 0224, UNC 0642, UNC 0631, UNC 0646, A-366 (Sweis et al. (2014) ACS Med. Chem. Lett., 5(2):205-209), etc.), and histone deacetylase (HDAC) inhibitors. In a particular embodiment, the fetal hemoglobin inducer is a histone methyltransferase (HMT) inhibitor, particularly UNC0638. In a particular embodiment, the fetal hemoglobin inducer is pomalidomide or hydroxyurea, particularly pomalidomide. The eIF2αK1 inhibitor and the fetal hemoglobin inducer can be administered to the subject sequentially or consecutively (e.g., in different compositions) and/or at the same time (e.g., in the same composition).

eIF2αK1 inhibitors are compounds which reduce eIF2αK1 activity (particularly its kinase activity) and/or the expression of eIF2αK1. In a particular embodiment, the eIF2αK1 inhibitor is specific to eIF2αK1. In a particular embodiment, the eIF2αK1 inhibitor reduces eIF2αK1 activity and/or expression to greater levels than other eukaryotic translation initiation factor 2-alpha kinases (e.g., eIF2αK2, eIF2αK3, or eIF2αK4). Examples of eIF2αK1 inhibitors include, without limitation, proteins, polypeptides, peptides, antibodies, small molecules, and nucleic acid molecules. In a particular embodiment, the eIF2αK1 inhibitor is a kinase domain inhibitor or heme binding domain inhibitor. In another embodiment, the eIF2αK1 inhibitor is an inhibitory nucleic acid molecule, such as an antisense, siRNA, or shRNA molecule (or a nucleic acid molecule encoding the inhibitory nucleic acid molecule). In a particular embodiment, the eIF2αK1 inhibitor is a CRISPR based targeting of the eIF2αK1 gene (e.g., with a guide RNA targeting the eIF2αK1 gene). In a particular embodiment, the eIF2αK1 inhibitor is a small molecule.

A variety of eIF2αK1 inhibitors are known in the art. As stated hereinabove, heme is an inhibitor of eIF2αK1 activity. Heme metabolites and heme synthesis intermediates have also been shown to inhibit eIF2αK1 activity (Miksanova et al. (2006) Biochem., 45:9894-9905). More specifically, Fe(III)-hemin, Fe(II)-heme, protoporphyrin IX, bilirubin, biliverdin, and uroporphyrin have been shown to inhibit eIF2αK1 activity (Miksanova et al. (2006) Biochem., 45:9894-9905). Quercetin has also been identified as an ATP-competitive kinase inhibitor of eIF2αK1 (Srivastava et al. (1986) Prog. Clin. Biol. Res., 213:315-8; Kanelakis et al. (2009) Adv. Hematol., 251915). A series of aminopyrazoloindanes have also been shown to be effective inhibitors of eIF2αK1 (Rosen et al. (2009) Bioorg. Med. Chem. Lett., 19(23):6548-51; incorporated herein by reference for the aminopyrazoloindane inhibitors of eIF2αK1, particularly those in Tables 2, 3, and 4). In a particular embodiment, the eIF2αK1 inhibitor is a synthetic or non-natural compound.

Clustered, regularly interspaced, short palindromic repeat (CRISPR)/Cas9 (e.g., from Streptococcus pyogenes) technology and gene editing are well known in the art (see, e.g., Sander et al. (2014) Nature Biotech., 32:347-355; Jinek et al. (2012) Science, 337:816-821; Cong et al. (2013) Science 339:819-823; Ran et al. (2013) Nature Protocols 8:2281-2308; Mali et al. (2013) Science 339:823-826; addgene.org/crispr/guide/). The RNA-guided CRISPR/Cas9 system involves expressing Cas9 along with a guide RNA molecule (gRNA). When coexpressed, gRNAs bind and recruit Cas9 to a specific genomic target sequence where it mediates a double strand DNA (dsDNA) break. The binding specificity of the CRISPR/Cas9 complex depends on two different elements. First, the binding complementarity between the targeted genomic DNA (genDNA) sequence and the complementary recognition sequence of the gRNA (e.g., ˜18-22 nucleotides, particularly about 20 nucleotides). Second, the presence of a protospacer-adjacent motif (PAM) juxtaposed to the genDNA/gRNA complementary region (Jinek et al. (2012) Science 337:816-821; Hsu et al. (2013) Nat. Biotech., 31:827-832; Sternberg et al. (2014) Nature 507:62-67). The PAM motif for S. Pyogenes Cas9 has been fully characterized, and is NGG or NAG (Jinek et al. (2012) Science 337:816-821; Hsu et al. (2013) Nat. Biotech., 31:827-832). Other PAMs of other Cas9 are also known (see, e.g., addgene.org/crispr/guide/#pam-table). Guidelines and computer-assisted methods for generating gRNAs are available (see, e.g, CRISPR Design Tool (crispr.mit.edu/); Hsu et al. (2013) Nat. Biotechnol. 31:827-832; addgene.org/CRISPR; and CRISPR gRNA Design tool—DNA2.0 (dna20.com/eCommerce/startCas9)). Typically, the PAM sequence is 3′ of the DNA target sequence in the genomic sequence.

In a particular embodiment, the method comprises administering at least one Cas9 (e.g., a nucleic acid molecule encoding Cas9) and at least one gRNA (e.g., a nucleic acid molecule encoding the gRNA) to the cell or subject. In a particular embodiment, the Cas9 is S. pyogenes Cas9. In a particular embodiment, the targeted PAM is in the 5′UTR, promoter, or first intron. When present, a second gRNA is provided which targets anywhere from the 5′UTR to the 3′UTR of the gene, particularly within the first intron. The nucleic acids of the instant invention may be administered consecutively (before or after) and/or at the same time (concurrently). The nucleic acid molecules may be administered in the same composition or in separate compositions. In a particular embodiment, the nucleic acid molecules are delivered in a single vector (e.g., a viral vector).

In a particular embodiment, the nucleic acid molecules of the instant invention are delivered (e.g., via infection, transfection, electroporation, etc.) and expressed in cells via a vector (e.g., a plasmid), particularly a viral vector. The expression vectors of the instant invention may employ a strong promoter, a constitutive promoter, and/or a regulated promoter. In a particular embodiment, the nucleic acid molecules are expressed transiently. Examples of promoters are well known in the art and include, but are not limited to, RNA polymerase II promoters, the T7 RNA polymerase promoter, and RNA polymerase III promoters (e.g., U6 and H1; see, e.g., Myslinski et al. (2001) Nucl. Acids Res., 29:2502-09). Examples of expression vectors for expressing the molecules of the invention include, without limitation, plasmids and viral vectors (e.g., adeno-associated viruses (AAVs), adenoviruses, retroviruses, and lentiviruses).

In a particular embodiment, the guide RNA of the instant invention may comprise separate nucleic acid molecules. For example, one RNA may specifically hybridize to a target sequence (crRNA) and another RNA (trans-activating crRNA (tracrRNA)) specifically hybridizes with the crRNA. In a particular embodiment, the guide RNA is a single molecule (sgRNA) which comprises a sequence which specifically hybridizes with a target sequence (crRNA; complementary sequence) and a sequence recognized by Cas9 (e.g., a tracrRNA sequence; scaffold sequence). Examples of gRNA scaffold sequences are well known in the art (e.g., 5′-GUUUUAGAGC UAGAAAUAGC AAGUUAAAAU AAGGCUAGUC CGUUAUCAAC UUGAAAAAGU GGCACCGAGU CGGUGCUUUU; SEQ ID NO: 18). As used herein, the term “specifically hybridizes” does not mean that the nucleic acid molecule needs to be 100% complementary to the target sequence. Rather, the sequence may be at least 80%, 85%, 90%, 95%, 97%, 99%, or 100% complementary to the target sequences (e.g., the complementary between the gRNA and the genomic DNA). The greater the complementarity reduces the likelihood of undesired cleavage events at other sites of the genome. In a particular embodiment, the region of complementarity (e.g., between a guide RNA and a target sequence) is at least about 10, at least about 12, at least about 15, at least about 17, at least about 20, at least about 25, at least about 30, at least about 35, or more nucleotides. In a particular embodiment, the region of complementarity (e.g., between a guide RNA and a target sequence) is about 15 to about 25 nucleotides, about 15 to about 23 nucleotides, about 16 to about 23 nucleotides, about 17 to about 21 nucleotides, about 18 to about 22 nucleotides, or about 20 nucleotides. In a particular embodiment, the guide RNA targets a sequence or comprises a sequence (inclusive of RNA version of DNA molecules) as set forth in the Example provided herein (see, e.g., the sequences provided in Table 1 (e.g., gRNA1, gRNA2, gRNA3, gRNA4, gRNA5, or gRNA6, particularly gRNA3 or gRNA5)). In a particular embodiment, the guide RNA targets a sequence or comprises a sequence which has at least 80%, 85%, 90%, 95%, 97%, 99%, or 100% homology or identity to a sequence set forth in the Example (e.g., Table 1 provided herein; (e.g., gRNA1, gRNA2, gRNA3, gRNA4, gRNA5, or gRNA6, particularly gRNA3 or gRNA5)). The sequences may be extended or shortened by 1, 2, 3, 4, or 5 nucleotides at the end of the sequence opposite from the PAM (e.g., at the 5′ end). When the sequence is extended the added nucleotides should correspond to the genomic sequence.

The above methods also encompass ex vivo methods. For example, the methods of the instant invention can comprise isolating hematopoietic cells (e.g., erythroid precursor cells) or erythroid cells from a subject, delivering at least one eIF2αK1 inhibitor to the cells, and administering the treated cells to the subject. The isolated cells may also be treated with other reagents in vitro, such as at least one fetal hemoglobin inducer, prior to administration to the subject. In a particular embodiment, the cells are not fully mature, anucleated erythrocytes.

The methods of the instant invention may further comprise monitoring the disease or disorder in the subject after administration of the composition(s) of the instant invention to monitor the efficacy of the method. For example, the subject may be monitored for characteristics of low hemoglobin or a hemoglobinopathy.

When an inhibitory nucleic acid molecule is delivered to a cell or subject, the inhibitory nucleic acid molecule may be administered directly or an expression vector may be used. In a particular embodiment, the inhibitory nucleic acid molecules are delivered (e.g., via infection, transfection, electroporation, etc.) and expressed in cells via a vector (e.g., a plasmid), particularly a viral vector. The expression vectors of the instant invention may employ a strong promoter, a constitutive promoter, and/or a regulated promoter. In a particular embodiment, the inhibitory nucleic acid molecules are expressed transiently. In a particular embodiment, the promoter is cell-type specific (e.g., erythroid cells). Examples of promoters are well known in the art and include, but are not limited to, RNA polymerase II promoters, the T7 RNA polymerase promoter, and RNA polymerase III promoters (e.g., U6 and H1; see, e.g., Myslinski et al. (2001) Nucl. Acids Res., 29:2502-09). Examples of expression vectors for expressing the molecules of the invention include, without limitation, plasmids and viral vectors (e.g., adeno-associated viruses (AAVs), adenoviruses, retroviruses, and lentiviruses).

As explained hereinabove, the compositions of the instant invention are useful for increasing hemoglobin production and for treating hemoglobinopathies and thalassemias. A therapeutically effective amount of the composition may be administered to a subject in need thereof. The dosages, methods, and times of administration are readily determinable by persons skilled in the art, given the teachings provided herein.

The components as described herein will generally be administered to a patient as a pharmaceutical preparation. The term “patient” or “subject” as used herein refers to human or animal subjects. The components of the instant invention may be employed therapeutically, under the guidance of a physician for the treatment of the indicated disease or disorder.

The pharmaceutical preparation comprising the components of the invention may be conveniently formulated for administration with an acceptable medium (e.g., pharmaceutically acceptable carrier) such as water, buffered saline, ethanol, polyol (for example, glycerol, propylene glycol, liquid polyethylene glycol and the like), dimethyl sulfoxide (DMSO), oils, detergents, suspending agents or suitable mixtures thereof. The concentration of the agents in the chosen medium may be varied and the medium may be chosen based on the desired route of administration of the pharmaceutical preparation. Except insofar as any conventional media or agent is incompatible with the agents to be administered, its use in the pharmaceutical preparation is contemplated.

The compositions of the present invention can be administered by any suitable route, for example, by injection (e.g., for local (direct) or systemic administration), oral, pulmonary, topical, nasal or other modes of administration. The composition may be administered by any suitable means, including parenteral, intramuscular, intravenous, intraarterial, intraperitoneal, subcutaneous, topical, inhalatory, transdermal, intrapulmonary, intraareterial, intrarectal, intramuscular, and intranasal administration. In a particular embodiment, the composition is administered directly to the blood stream (e.g., intravenously). In general, the pharmaceutically acceptable carrier of the composition is selected from the group of diluents, preservatives, solubilizers, emulsifiers, adjuvants and/or carriers. The compositions can include diluents of various buffer content (e.g., Tris HCl, acetate, phosphate), pH and ionic strength; and additives such as detergents and solubilizing agents (e.g., polysorbate 80), anti oxidants (e.g., ascorbic acid, sodium metabisulfite), preservatives (e.g., Thimersol, benzyl alcohol) and bulking substances (e.g., lactose, mannitol). The compositions can also be incorporated into particulate preparations of polymeric compounds such as polyesters, polyamino acids, hydrogels, polylactide/glycolide copolymers, ethylenevinylacetate copolymers, polylactic acid, polyglycolic acid, etc., or into liposomes. Such compositions may influence the physical state, stability, rate of in vivo release, and rate of in vivo clearance of components of a pharmaceutical composition of the present invention. See, e.g., Remington: The Science and Practice of Pharmacy, 21st edition, Philadelphia, Pa. Lippincott Williams & Wilkins. The pharmaceutical composition of the present invention can be prepared, for example, in liquid form, or can be in dried powder form (e.g., lyophilized for later reconstitution).

As used herein, “pharmaceutically acceptable carrier” includes any and all solvents, dispersion media and the like which may be appropriate for the desired route of administration of the pharmaceutical preparation, as exemplified in the preceding paragraph. The use of such media for pharmaceutically active substances is known in the art. Except insofar as any conventional media or agent is incompatible with the molecules to be administered, its use in the pharmaceutical preparation is contemplated.

Pharmaceutical compositions containing a compound of the present invention as the active ingredient in intimate admixture with a pharmaceutical carrier can be prepared according to conventional pharmaceutical compounding techniques. The carrier may take a wide variety of forms depending on the form of preparation desired for administration, e.g., intravenous. Injectable suspensions may be prepared, in which case appropriate liquid carriers, suspending agents and the like may be employed. Pharmaceutical preparations for injection are known in the art. If injection is selected as a method for administering the therapy, steps should be taken to ensure that sufficient amounts of the molecules reach their target cells to exert a biological effect.

A pharmaceutical preparation of the invention may be formulated in dosage unit form for ease of administration and uniformity of dosage. Dosage unit form, as used herein, refers to a physically discrete unit of the pharmaceutical preparation appropriate for the patient undergoing treatment. Each dosage should contain a quantity of active ingredient calculated to produce the desired effect in association with the selected pharmaceutical carrier. Procedures for determining the appropriate dosage unit are well known to those skilled in the art. Dosage units may be proportionately increased or decreased based on the weight of the patient. Appropriate concentrations for alleviation of a particular pathological condition may be determined by dosage concentration curve calculations, as known in the art. The appropriate dosage unit for the administration of the molecules of the instant invention may be determined by evaluating the toxicity of the molecules in animal models. Various concentrations of pharmaceutical preparations may be administered to mice with transplanted human tumors, and the minimal and maximal dosages may be determined based on the results of significant reduction of tumor size and side effects as a result of the treatment. Appropriate dosage unit may also be determined by assessing the efficacy of the treatment in combination with other standard therapies.

The pharmaceutical preparation comprising the molecules of the instant invention may be administered at appropriate intervals, for example, at least twice a day or more until the pathological symptoms are reduced or alleviated, after which the dosage may be reduced to a maintenance level. The appropriate interval in a particular case would normally depend on the condition of the patient.

Definitions

The singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise.

The terms “isolated” is not meant to exclude artificial or synthetic mixtures with other compounds or materials, or the presence of impurities that do not interfere with the fundamental activity, and that may be present, for example, due to incomplete purification, or the addition of stabilizers.

“Pharmaceutically acceptable” indicates approval by a regulatory agency of the Federal or a state government or listed in the U.S. Pharmacopeia or other generally recognized pharmacopeia for use in animals, and more particularly in humans.

A “carrier” refers to, for example, a diluent, adjuvant, preservative (e.g., Thimersol, benzyl alcohol), anti-oxidant (e.g., ascorbic acid, sodium metabisulfite), solubilizer (e.g., polysorbate 80), emulsifier, buffer (e.g., Tris HCl, acetate, phosphate), antimicrobial, bulking substance (e.g., lactose, mannitol), excipient, auxilliary agent or vehicle with which an active agent of the present invention is administered. Pharmaceutically acceptable carriers can be sterile liquids, such as water and oils, including those of petroleum, animal, vegetable or synthetic origin. Water or aqueous saline solutions and aqueous dextrose and glycerol solutions are preferably employed as carriers, particularly for injectable solutions. Suitable pharmaceutical carriers are described in Remington: The Science and Practice of Pharmacy, (Lippincott, Williams and Wilkins); Liberman, et al., Eds., Pharmaceutical Dosage Forms, Marcel Decker, New York, N.Y.; and Rowe, et al., Eds., Handbook of Pharmaceutical Excipients, Pharmaceutical Pr.

The term “treat” as used herein refers to any type of treatment that imparts a benefit to a patient suffering from an injury, including improvement in the condition of the patient (e.g., in one or more symptoms), delay in the progression of the condition, etc.

As used herein, the term “prevent” refers to the prophylactic treatment of a subject who is at risk of developing a condition and/or sustaining an injury, resulting in a decrease in the probability that the subject will develop conditions associated with the hemoglobinopathy or thalassemia.

A “therapeutically effective amount” of a compound or a pharmaceutical composition refers to an amount effective to prevent, inhibit, or treat a particular injury and/or the symptoms thereof. For example, “therapeutically effective amount” may refer to an amount sufficient to modulate the pathology associated with a hemoglobinopathy or thalassemia.

As used herein, the term “subject” refers to an animal, particularly a mammal, particularly a human.

A “vector” is a genetic element, such as a plasmid, cosmid, bacmid, phage or virus, to which another genetic sequence or element (either DNA or RNA) may be attached so as to bring about the replication and/or expression of the attached sequence or element. A vector may be either RNA or DNA and may be single or double stranded. A vector may comprise expression operons or elements such as, without limitation, transcriptional and translational control sequences, such as promoters, enhancers, translational start signals, polyadenylation signals, terminators, and the like, and which facilitate the expression of a polynucleotide or a polypeptide coding sequence in a host cell or organism.

As used herein, the term “small molecule” refers to a substance or compound that has a relatively low molecular weight (e.g., less than 4,000, less than 2,000, particularly less than 1 kDa or 800 Da). Typically, small molecules are organic, but are not proteins, polypeptides, amino acids, or nucleic acids.

The phrase “small, interfering RNA (siRNA)” refers to a short (typically less than 30 nucleotides long, particularly 12-30 or 20-25 nucleotides in length) double stranded RNA molecule. Typically, the siRNA modulates the expression of a gene to which the siRNA is targeted. Methods of identifying and synthesizing siRNA molecules are known in the art (see, e.g., Ausubel et al., Current Protocols in Molecular Biology, John Wiley and Sons, Inc). Short hairpin RNA molecules (shRNA) typically consist of short complementary sequences separated by a small loop sequence wherein one of the sequences is complimentary to the gene target. shRNA molecules are typically processed into an siRNA within the cell by endonucleases. Exemplary modifications to siRNA molecules are provided in U.S. Application Publication No. 20050032733. For example, siRNA and shRNA molecules may be modified with nuclease resistant modifications (e.g., phosphorothioates, locked nucleic acids (LNA), 2′-O-methyl modifications, or morpholino linkages). Expression vectors for the expression of siRNA or shRNA molecules may employ a strong promoter which may be constitutive or regulated. Such promoters are well known in the art and include, but are not limited to, RNA polymerase II promoters, the T7 RNA polymerase promoter, and the RNA polymerase III promoters U6 and H1 (see, e.g., Myslinski et al. (2001) Nucl. Acids Res., 29:2502 09).

“Antisense nucleic acid molecules” or “antisense oligonucleotides” include nucleic acid molecules (e.g., single stranded molecules) which are targeted (complementary) to a chosen sequence (e.g., to translation initiation sites and/or splice sites) to inhibit the expression of a protein of interest. Such antisense molecules are typically between about 15 and about 50 nucleotides in length, more particularly between about 15 and about 30 nucleotides, and often span the translational start site of mRNA molecules. Antisense constructs may also be generated which contain the entire sequence of the target nucleic acid molecule in reverse orientation. Antisense oligonucleotides targeted to any known nucleotide sequence can be prepared by oligonucleotide synthesis according to standard methods. Antisense oligonucleotides may be modified as described above to comprise nuclease resistant modifications.

The following example is provided to illustrate various embodiments of the present invention. It is not intended to limit the invention in any way.

Example

A CRISPR screening strategy (Shi et al. (2015) Nat. Biotechnol., 33(6):661-7) was employed to identify regulators of fetal globin expression. Clustered, regularly interspaced, short palindromic repeat (CRISPR)/Cas9 technology is well known in the art (see, e.g., Sander et al. (2014) Nature Biotech., 32:347-355; Jinek et al. (2012) Science, 337:816-821; Cong et al. (2013) Science 339:819-823; Ran et al. (2013) Nature Protocols 8:2281-2308; Mali et al. (2013) Science 339:823-826). Cas9 possesses two nuclease domains, a RuvC-like nuclease domain and a HNH-like nuclease domain, and is responsible for the destruction of the target DNA (Jinek et al. (2012) Science, 337:816-821; Sapranauskas et al. (2011) Nucleic Acids Res. 39:9275-9282). The two nucleases generate double-stranded breaks. The double-stranded endonuclease activity of Cas9 requires a target sequence (e.g., ˜20 nucleotides, see above) and a short conserved sequence (˜2-5 nucleotides; e.g., 3 nucleotides) known as protospacer-associated motif (PAM), which follows immediately 3′—of the CRISPR RNA (crRNA) complementary sequence (Jinek et al. (2012) Science, 337:816-821; Nishimasu et al. (2014) Cell 156(5):935-49; Swarts et al. (2012) PLoS One, 7:e35888; Sternberg et al. (2014) Nature 507(7490):62-7). The double strand break can be repaired by non-homologous end joining (NHEJ) pathway yielding an insertion and/or deletion or, in the presence of a donor template, by homology-directed repair (HDR) pathway for replacement mutations (Overballe-Petersen et al. (2013) Proc. Natl. Acad. Sci. U.S.A. 110:19860-19865; Gong et al. (2005) Nat. Struct. Mol. Biol. 12:304-312). The RNA-guided CRISPR/Cas9 system involves expressing Cas9 along with a guide RNA molecule (gRNA). When coexpressed, gRNAs bind and recruit Cas9 to a specific genomic target sequence where it mediates a double strand DNA (dsDNA) break and activates the dsDNA break repair machinery. Specific DNA fragments can be deleted when two gRNA/Cas9 complexes generate dsDNA breaks at relative proximity, and the genomic DNA is repaired by nonhomologous end joining.

Briefly, cells from a human umbilical cord blood-derived erythroid cells progenitor cell line (HUDEP2) expressing Cas9 were transduced with a lentiviral library of guideRNAs (gRNAs). The library targeted over 500 different kinase domains with 6 guides per domain (i.e., over 3000 independent guides). Cells were then stained with fetal hemoglobin antibody and positive cells were sorted. The results showed that all 6 guides for eIF2αK1 resulted in enriched fetal globin expression.

These results were confirmed in HUDEP-2 cells by individually expressing each one of the six gRNAs targeting eIF2αK1, a gRNA targeting BCL11A exon 2 (positive control; BCL11A is a repressor of HbF expression), one of two gRNAs targeting death associated protein kinase 2 (DAPK2), one of two gRNAs targeting transforming growth factor beta receptor 2 (TGFBR2), or a negative control gRNA.

Table 1 provides sequences of the gRNAs fluorescence-activated cell sorting (FACS) with an HbF antibody shows that the eIF2αK1 gRNAs significantly increased expression of HbF compared to the other gRNAs and negative controls (FIG. 1A). A quantitative reverse transcription PCR (RT-qPCR) analysis was also performed on the above cells to measure mRNA levels. As seen in FIG. 1B, the eIF2αK1 gRNAs significantly increased gamma globin RNA levels compared to the other gRNAs and negative controls. FIG. 1C provides a representative FACS analysis for sgRNA #5 showing increased HbF production. FIG. 1D provides a graph of HbF flow cytometry of cells expressing indicated sgRNAs over two experiments. Western blot analysis confirmed the decreased expression of eIF2αK1 (HRI) and increased expression of γ-globin with sgRNA #3 and sgRNA #5.

TABLE 1 gRNA sequences. CRISPR sgRNA name Target Sequence SEQ ID NO BCL11A Exon2 TGAACCAGACCACGGCCCGT 1 sgRNA eIF2αK1 sgRNA1 TCTGGAAGTGCTCTCCGACC 2 eIF2αK1 sgRNA2 GTATCCACCTTTTCCTAAGA 3 eIF2αK1 sgRNA3 TTTTAGTTGCACCCTTAATC 4 eIF2αK1 sgRNA4 TTGTTGGCTATCACACCGCG 5 eIF2αK1 sgRNA5 ATAGTCGAGAGAAACAAGCG 6 eIF2αK1 sgRNA6 TGGTGAACTTGAGTCGACCC 7 Neg02 sgRNA GACCGGAACGATCTCGCGTA 8

In addition to the above, a whole proteome mass spectrometry analysis of cells transduced with a gRNA targeting eIF2αK1 was performed. As seen in FIG. 2, fetal globin expression increased more than two fold upon transduction with eIF2αK1 gRNA #3 or gRNA #5.

Combination experiments with the immunomodulatory pomalidomide, which is an HbF inducer, were also performed. If eIF2αK1 inhibition works at least in part by altering protein translation, additive effects may be observed when using compounds that predominantly affect transcription of fetal globin genes. Briefly, HUDEP-2 expressing Cas9 cells were transduced with eIF2αK1 gRNA #3, eIF2αK1 gRNA #5, a gRNA targeting BCL11A exon 2, or a negative control gRNA. The cells were then incubated with or without pomalidomide. As seen in FIG. 3, the combination of eIF2αK1 inhibition and pomalidomide greatly increased the number of HbF positive cells. Indeed, the results with pomalidomide in combination with eIF2αK1 inhibition were very strong in three independent experiments, even stronger than those observed with Bcl11A inhibition and pomalidomide. This demonstrates that a compound that inhibits eIF2αK1 can be combined with pomalidomide or other HbF inducers to achieve a greater therapeutic index.

In additional experiments, eIF2αK1 was knocked down in primary human erythroid cells using shRNAs, as editing was not efficient enough in primary cells. Fetal hemoglobin was found to be upregulated in a manner comparable to or exceeding that of Bcl11A depletion (positive control). As seen in FIG. 4, two of the four shRNA (#1 and #4) dramatically increased HbF production in human primary cells. Table 2 provides the sequences of the shRNA molecules.

TABLE 2 shRNA sequences. shRNA name Target Sequence SEQ ID NO ZBTB7A shRNA2 AAGTCGATCTCGTACACGTTC  9 ZBTB7A shRNA4 AATAGGTTTGTGTCTCAGTGG 10 BCL11A shRNA1 AATCCATGAGTGTTCTGTGCG 11 BCL11A shRNA2 TAAACAATCGTCATCCTCTGG 12 eIF2αK1 shRNA1 TTAACACCACATTGCTCTCTG 13 eIF2αK1 shRNA2 ATTAAGTGAGTAATAGCTCTG 14 eIF2αK1 shRNA3 TAAACGTCTGGCAAAGTAGC 15 eIF2αK1 shRNA4 TAAACCTGTTAGAACTTCTGC 16 SC shRNA AAATTATTAGCGCTATCGCGC 17

FIG. 5A provides a representative HbF flow cytometry on day 14 of CD34+ erythroid differentiation. LRF shRNA and shRNA 1 and 2 increased HbF expression. Leukemia/lymphoma-related factor (LRF), as with BCL11A, represses expression of fetal hemoglobin (Masuda et al. (2016) Science 351(6270): 285-289). FIG. 5B provides a summary of HbF flow cytometry experiments. FIG. 5C provides γ-globin mRNA as fraction of γ-globin+β-globin by RT-qPCR on day 12. FIG. 5D provides RNA-seq for CD34+ cells on day 12. FIG. 5E shows an HPLC analysis of samples from cell expressing annotated shRNAs, at day 14 of differentiation. FIG. 5F provides images of sickle cell patient-derived erythroid cultures showing that eIF2αK1 shRNA1 and eIF2αK1 shRN2 decreased the number of sickle cells.

Further experiments demonstrate that HRI regulates BCL11A protein levels. Western blot analyses were performed with indicated antibodies (FIG. 6A) in cells uninfected, or infected with virus expressing scrambled or HRI shRNAs on day 14 of differentiation. BCL11A expression is decreased with HRI shRNAs. FIG. 6A also shows BCL11A mRNA levels in HRI knock down cells as fraction of SC shRNA expressing cells. FIG. 6B shows BCL11A cDNA rescue in HRI depleted HUDEP2 clonal cell lines.

While certain of the preferred embodiments of the present invention have been described and specifically exemplified above, it is not intended that the invention be limited to such embodiments. Various modifications may be made thereto without departing from the scope and spirit of the present invention, as set forth in the following claims. 

What is claimed is:
 1. A method of increasing the level of fetal hemoglobin in a cell or subject, the method comprising administering at least one eukaryotic translation initiation factor 2-alpha kinase 1 (eIF2αK1) inhibitor to the cell or subject.
 2. The method of claim 1, wherein the subject has a β-chain hemoglobinopathy.
 3. The method of claim 1, wherein the subject has thalassemia.
 4. The method of claim 1, wherein the subject has sickle cell anemia.
 5. The method of claim 1, wherein the eIF2αK1 inhibitor is a small molecule.
 6. The method of claim 1, wherein the eIF2αK1 inhibitor is a kinase domain inhibitor or a heme binding domain inhibitor.
 7. The method of claim 1, wherein the cell is an erythroid cell.
 8. The method of claim 1, further comprising administering at least one fetal hemoglobin inducer to the cell or subject.
 9. The method of claim 8, wherein said fetal hemoglobin inducer is pomalidomide.
 10. The method of claim 8, wherein said fetal hemoglobin inducer is a histone methyltransferase (HMT) inhibitor.
 11. The method of claim 10, wherein said HMT inhibitor is UNC0638.
 12. A method of treating a hemoglobinopathy in a subject in need thereof, the method comprising administering a composition comprising at least one eukaryotic translation initiation factor 2-alpha kinase 1 (eIF2αK1) inhibitor and a pharmaceutically acceptable carrier to the subject.
 13. The method of claim 12, wherein the subject has a β-chain hemoglobinopathy.
 14. The method of claim 12, wherein the subject has thalassemia.
 15. The method of claim 12, wherein the subject has sickle cell anemia.
 16. The method of claim 12, wherein the eIF2αK1 inhibitor is a small molecule.
 17. The method of claim 12, wherein the eIF2αK1 inhibitor is a kinase domain inhibitor or a heme binding domain inhibitor.
 18. The method of claim 12, further comprising administering at least one fetal hemoglobin inducer to the subject.
 19. The method of claim 18, wherein said fetal hemoglobin inducer is pomalidomide.
 20. The method of claim 18, wherein said fetal hemoglobin inducer is a histone methyltransferase (HMT) inhibitor.
 21. The method of claim 20, wherein said HMT inhibitor is UNC0638.
 22. The method of claim 12, wherein the eIF2αK1 inhibitor is contained within a cell administered to the subject. 